diff --git a/example/1D-Cellular-Automota.forth b/example/1D-Cellular-Automota.forth index b7fbdd9..6bce6a0 100644 --- a/example/1D-Cellular-Automota.forth +++ b/example/1D-Cellular-Automota.forth @@ -1,4 +1,4 @@ -# example|RosettaCode|1D-Cellular-Automota +# 1D Cellular Automota Assume an array of cells with an initial distribution of live and dead cells, and imaginary cells off the end of the array having fixed values. @@ -15,12 +15,6 @@ If, in the following table, a live cell is represented by 1 and a dead cell by 0 110 -> 1 # Needs one neighbour to survive 111 -> 0 # Starved to death. -Declare module constant (prevents reloading when using `import`): - -~~~ -:example|RosettaCode|1D-Cellular-Automota ; -~~~ - I had originally written an implementation of this in RETRO 11. For RETRO 12 I took advantage of new language features and some further considerations into the rules for this task. The first word, `string,` inlines a string to `here`. I'll use this to setup the initial input. diff --git a/example/99Bottles.forth b/example/99Bottles.forth index cf51840..baa7552 100644 --- a/example/99Bottles.forth +++ b/example/99Bottles.forth @@ -1,4 +1,4 @@ -# example|99Bottles +# 99 Bottles Display the text for the *99 Bottles of Beer* song. diff --git a/example/accumulator.forth b/example/accumulator.forth index 8c00c82..0c85e28 100644 --- a/example/accumulator.forth +++ b/example/accumulator.forth @@ -1,23 +1,42 @@ -Traditional Forth has a CREATE/DOES> construct. RETRO allows for -something similar using the `does` combinator. +# Accumulator -An example in traditional Forth: +## Description + +This implements a function that takes an initial value and constructs a new function that returns the value before incrementing the stored value by 1. + +So, given an initial value of 1, the first time the function is called, 1 is returned. The second, 2, and so on. + +In traditional Forth, this would be done using a CREATE/DOES> construct. RETRO allows for something similar using the `does` combinator. + +An example in a traditional Forth: : acc ( n "name" -- ) create , does> dup >r @ dup 1+ r> ! ; -And in RETRO, using `does` and the `bi` combinator: +In RETRO, we could begin by rewriting this using the RETRO words: + + :acc (ns-) + d:create , [ dup push fetch n:inc pop store ] does ; + +The `dup push ... pop` pattern is the `sip` combinator, so we can simplify it: + + :acc (ns-) + d:create , [ [ fetch n:inc ] sip store ] does ; + +This is better, but not quite done. RETRO has a `v:inc` for incrementing variables, which would eliminate the n:inc and store. And a `bi` combinator to run two quotes against a value. So we could simplify yet again, resulting in: ~~~ :acc (ns-) d:create , [ [ fetch ] [ v:inc ] bi ] does ; ~~~ -Here's a little test case: +This removes the primitive stack shuffling, and leaves something that expresses the intent more clearly. -~~~ -#10 'foo acc -foo -foo -foo -~~~ +Finally, here's a little test case: + +``` + #10 'foo acc + foo + foo + foo +```